This is a TEST version, so be prepared to have some issues. Do not use it for production.
NEW FEATURES SINCE LAST RELEASE
New v4 XB4 features (please check at https://render.otoy.com/forum/viewtopic.php?f=33&t=68283).
- Support universal material
- support light linking
- Global light exclusion: “Render-Octane Kernal-Light”
- Light linking for object: “Data-Octane Properties-Light pass mask”
- Support new AI light and settings
- Support UDIM
- “Node graph-Octane Texture-Octane Image Tile Tex”
- Support new light passes in v4 XB4(direct/indirect(ambient light, sunlight, light pass 1-8))
- New features and refactored systems(these are included in 16.1).
- New Render Pass System(including all passes and optinos in v4 xb4 SA)
- New Passes: refract filter, transmission filter, postprocess, all lighting passes(ambient light, sunlight, light pass 1~8), position, texture tangent, motion vector, light pass id, render layer id, render layer mask, wireframe, object layer color, Baking Group ID, all Material Passes (opacity, roughness, ior, diffuse filter, reflection filter, refraction filter, transmission filter)
- New Options: include environment, uv coordinate selection
Fix bugs:
- use rgba color for object id and material id passes
- support scatter conversion with instance ids for duplication/array modifier/particle system
- support node group.
- now node group input value can be resolved independently in different materials.
FIXES SINCE LAST RELEASE
- Add AI Light update and AI Light strength
- Report warning when rendering denoise passes without enabling denoise
- Add point type to draw bounds as points
- Fix bug: Blend Angle option in the Triplanar Mapping node is not working
This has support for both Linux and OSX now. happy dance 
I did a quick test to compare stand alone and the plugin:
I did a render to 500 s/px and it took around 2.4 minutes. Then I rendered to 50 s/px with the denoiser turned on and it rendered in about 34 seconds. This is the image above. A bit slower than stand alone which rendered the image in about 19 seconds, but much, much better than the version 3 plugin, and a real speed boost from when the denoiser is not used.
Jason